[%c_effect b7;square;b7;type;Mistake;persistent;true]
41. f2e2  41... b7d7 [%c_effect d7;square;d7;type;Inaccuracy;persistent;true] This allows White to advance the pawn to f4, since capturing on e4 is no longer possible due to the pin. 42. f3f4 [%c_effect f4;square;f4;type;GreatFind;persistent;true] 42... e5f4 [%c_effect f4;square;f4;type;Inaccuracy;persistent;true] Carlsen goes down quickly. 43. g3f4 